1. Field of the Invention
This invention relates to a linear electrode construction for a fluorescent display device and a process for preparing the same, and more particularly to a linear electrode construction adapted to allow a fluorescent display device to carry out graphical display and the like with high density and a process for preparing the same.
2. Description of the Prior Art
A fluorescent display device is generally constructed to carry out luminous display by impinging electrons emitted from a filamentary cathode on an anode having a phosphor layer deposited thereon and selectively applied thereto anode potential. Such a fluorescent display device has been extensively used in a display system for various types of electronic devices, electric machines, and the like, because it provides good luminous display with low voltage, is low in power consumption, is driven directly by LSI and provides display different in luminous color depending upon phosphor to be used.
In such a fluorescent display device, it is highly desired to provide not only display of simple numeral or character but display of figure, image or the like as desired. Also, it is desired in the art to attain high densification of display in order to obtain dense display. Such high densification of display requires to arrange a plurality of linear electrodes such as control electrodes for selecting desired picture cells at intervals of 0.2-0.5 mm and at most 1 mm in a space defined between an anode and a cathode while keeping a distance between the linear electrodes and each of the anode and cathode. Also, this requires to uniformly apply suitable tension to the linear electrodes in order to prevent short-circuit due to the contact therebetween and absorb elongation thereof due to exposure of the linear electrodes to heating in the operation.
A conventional fluorescent display device adapted to provide graphical display and the like is generally constructed in a manner to stretch fine wires of a uniform section in a vacuum casing and lead out both ends of the wires to the vacuum casing without subjecting the ends of the wires to any treatment to form the connection with an external circuit. Thus, such linear electrode construction in the conventional device raises a problem that the connection between both ends of the wires and the external circuit is not satisfactory because the both ends have a highly small area of contact with the external circuit to render soldering therebetween difficult. Another problem encountered with the conventional linear electrode construction is that the intervals between the fine wires are apt to be non-uniform in the manufacturing process. Further, in the conventional construction, it is required to cut away the lead-out portions of the wires unnecessary for the connection with the external circuit. Nevertheless, it is highly troublesome to select such unnecessary lead-out wires. A further difficulty in the conventional linear electrode construction is that uniform tension is hard to be applied to all the wires because the wires have an extremely small section. Still a further problem is that the connection between the fine wires and the external circuit is readily injured because the lead-out portion of each wire is fine.
Thus, the conventional linear electrode construction does not allow a fluorescent display device to attain stable luminous display with high density.